Method of fabricating package structures

ABSTRACT

Some embodiments contemplate methods for forming a package structure and a package structure formed thereby. An embodiment method includes depositing a photosensitive dielectric layer on a support structure; forming a first layer on a surface of the photosensitive dielectric layer; exposing the photosensitive dielectric layer to radiation; and after the forming the first layer and the exposing to radiation, developing the photosensitive dielectric layer. The support structure includes an integrated circuit die. The layer has a different removal selectivity than the photosensitive dielectric layer during the developing. According to some embodiments, a thickness uniformity of the photosensitive dielectric layer after developing may be increased, and thickness loss from developing the photosensitive dielectric layer can be reduced.

This application is a continuation application of, and claims thebenefit of, U.S. Ser. No. 14/755,529, filed Jun. 30, 2015, now U.S. Pat.No. 9,741,586, entitled “Method of Fabricating Package Structures,”which application is incorporated herein in its entirety.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as, for example, personal computers, cell phones, digital cameras,and other electronic equipment. Semiconductor devices are typicallyfabricated by sequentially depositing insulating or dielectric layers,conductive layers, and semiconductor layers of material over asemiconductor substrate, and patterning the various material layersusing lithography to form circuit components and elements thereon.

The semiconductor industry continues to improve the integration densityof various electronic components (e.g., transistors, diodes, resistors,capacitors, etc.) by continual reductions in minimum feature size, whichallow more components to be integrated into a given area. In somedevices, multiple dies or packages with active devices or circuits arestacked vertically to reduce the footprint of a device package andpermit dies with different processing technologies to be interconnected.

Interconnections for this vertical stacking can be created on the topand bottom surfaces of a substrate by forming redistribution layers(RDLs) with conductive lines in insulating layers. The RDLs and the diesexternal to a particular package are electrically connected to dies inthe substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1 through 4 are cross sectional views of intermediate structuresof a first generic process in accordance with some embodiments.

FIG. 5 is a process flow of the first generic process in accordance withsome embodiments.

FIG. 6 illustrates a chemical reaction that may occur by treating anupper surface of a dielectric layer with hexamethyldisilazane (HMDS) gasin accordance with some embodiments.

FIGS. 7 through 10 are cross sectional views of intermediate structuresof a second generic process in accordance with some embodiments.

FIG. 11 is a process flow of the second generic process in accordancewith some embodiments.

FIGS. 12 through 16 are cross sectional views of intermediate structuresof a third generic process in accordance with some embodiments.

FIG. 17 is a process flow of the third generic process in accordancewith some embodiments.

FIGS. 18 through 31 are cross sectional views of intermediate stepsduring a process for forming a package structure in accordance with someembodiments.

FIG. 32 is a layout to illustrate aspects of scribe line regions inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments discussed herein may be discussed in a specific context,namely a fan-out or fan-in wafer-level package. Other embodimentscontemplate other applications, such as different package types ordifferent configurations that would be readily apparent to a person ofordinary skill in the art upon reading this disclosure. It should benoted that embodiments discussed herein may not necessarily illustrateevery component or feature that may be present in a structure. Forexample, multiples of a component may be omitted from a figure, such aswhen discussion of one of the component may be sufficient to conveyaspects of the embodiment. Further, method embodiments discussed hereinmay be discussed as being performed in a particular order; however,other method embodiments may be performed in any logical order.

FIGS. 1 through 4 illustrate cross sectional views of intermediatestructures of a first generic process to illustrate various generalconcepts according to some embodiments, and FIG. 5 is a process flow ofthe first generic process according to some embodiments. FIG. 1illustrates a support structure 46 with a first region 40, a secondregion 42, and a scribe line region 44 between the first region 40 andthe second region 42. The support structure 46 can include variousstructures formed in the first region 40 and the second region 42. Suchstructures can include an integrated circuit die, an encapsulatedintegrated circuit die, a substrate, or the like. An example of such astructure, and its formation, is illustrated in FIGS. 18 through 31.

As illustrated in FIG. 1 and in step 70 of FIG. 5, a dielectric layer 48is deposited on the support structure 46, such as by spin coating,lamination, or the like. The dielectric layer 48 is a photo-sensitivematerial, which can be positive or negative tone, and can further be apolymer, such as polybenzoxazole (PBO), polyimide, benzocyclobutene(BCB), or the like. In some embodiments, the dielectric layer 48 may bedeposited in a liquid state, such as by spin coating. The dielectriclayer 48 can be pre-baked or soft-baked in embodiments where thedielectric layer is deposited in a liquid state, such as at atemperature in a range from about 100° C. to about 125° C., like 120°C., at a duration in a range from about 60 seconds to about 600 seconds,such as 300 seconds. The pre-bake or soft-bake may be performed in situin, e.g., the spin coater chamber used to deposit the dielectric layer48. In embodiments where the dielectric layer is deposited in a liquidstate, a solvent in the liquid state dielectric layer 48 may evaporatesuch that, for example, 10% of the dielectric layer 48 is solvent, andthe dielectric layer 48 is in a semi-solid state. In some embodiments,the dielectric layer 48 upon deposition has a thickness in a range fromabout 6 μm to about 18 μm, such as about 16 μm to about 18 μm.

In FIG. 2 and step 72 of FIG. 5, a thin layer 50 is formed on an uppersurface of the dielectric layer 48. During this formation, thedielectric layer 48 can be in a solid or semi-solid state. In someembodiments, the formation of the thin layer 50 includes modifying theupper surface of the dielectric layer 48. The modification can includeexposing the upper surface to a precursor, such as ahexamethyldisilazane (HMDS) ([(CH₃)₃Si]₂NH) gas or the like. Further, insome embodiments, the upper surface of the dielectric layer 48 isexposed to the precursor, e.g., HMDS gas, in situ after the deposition.For example, if the dielectric layer 48 is deposited using spin coatingin a spin coater chamber, the HMDS gas can be provided in the spincoater chamber while the support structure 46 and dielectric layer 48remain in the spin coater chamber. The upper surface of the dielectriclayer 48 may be exposed to the precursor, e.g., the HMDS gas, using aflow rate of the precursor in a range from about 50 sccm to about 100sccm, such as about 50 sccm, at a temperature in a range from about 80°C. to about 150° C., such as about 100° C., for a duration in a rangefrom about 30 seconds to about 90 seconds, such as about 60 seconds.

FIG. 6 illustrates a chemical reaction that may occur by treating theupper surface of the dielectric layer 48 with HMDS gas. The uppersurface may have exposed hydroxide groups which when exposed to HMDS gascan react with the HMDS gas. Trimethylsilyl groups chemically bond withthe oxygen of the hydroxide groups to form a self-assembled monolayer(SAM) along the upper surface of the dielectric layer 48. In thisembodiment, the SAM may include hexamethyldisiloxane (HMDSO)(O[Si(CH₃)₃]₂). A byproduct of the reaction can be amidogen (NH₂). Theupper surface of the dielectric layer 48 may be unsaturated (asillustrated) or saturated with HMDSO to form the SAM. Further, the SAMmay include HMDS physically adsorbed on the upper surface of thedielectric layer 48 (not specifically illustrated). In theseembodiments, the SAM, which can include the HMDSO and/or HMDS, is thethin layer 50 as illustrated in FIG. 6. The SAM can have a thickness ina range from about 5 nm to about 50 nm, such as about 10 nm.

In other embodiments, the thin layer 50 can be a photo resist layerformed on the upper surface of the dielectric layer 48. The photo resistlayer can be a photo resist used in front-end of the line semiconductorprocessing and may be a nanometer scale layer. The thickness of thephoto resist layer can be in a range from about 80 nm to about 1000 nm,such as about 100 nm.

More generically, the formation of the thin layer 50 in step 72 caninclude any exposure to a gas, liquid, or material; treatment;deposition; or the like that improves removal selectivity betweenexposed and un-exposed portions of the dielectric layer 48 during asubsequent developing step. For example, the thin layer 50 can cause thedeveloping step to remove less of the un-exposed portions of thedielectric layer 48 compared to a removal of un-exposed portions of thedielectric layer without the thin layer 50. In some embodiments whereHMDS gas is used to modify a PBO dielectric layer, it has beendiscovered that a ratio of removal of exposed PBO to un-exposed PBOduring developing increased to 4.7, whereas a ratio of removal ofexposed PBO to un-exposed PBO during developing without a thin layerformation step was 3.4. The thin layer 50 can have a different removalselectivity than the dielectric layer 48. Hence, physical removal duringdeveloping can cause removal of soluble portions of the dielectric layer48 and overlying portions of the thin layer 50, while the thin layer 50over the non-soluble portions of the dielectric layer 48 generallyremains, which can reduce the chemical removal the non-soluble portionsof the dielectric layer 48.

In FIG. 3 and step 74 of FIG. 5, the dielectric layer 48 is exposed toradiation. A lithography mask 52 can be used during the exposure. Thelithography mask 52 can have a pattern that corresponds to a pattern tobe formed in the dielectric layer 48. Radiation 54 can be transmittedthrough and/or blocked by the lithography mask 52 to expose thedielectric layer 48 to the radiation 54 according to the pattern of thelithography mask 52. The radiation 54 can be, for example, a combinationof multiple wavelengths of light, such as a spectrum of g-, h-, andi-line having wavelengths of 436 nm, 405 nm, and 365 nm, respectively;ultraviolet radiation; far ultraviolet radiation, x-rays; electronbeams; or the like. In the illustrated embodiment, the dielectric layer48 is positive tone such that portions of the dielectric layer 48exposed to the radiation 54 though the lithography mask 52 becomesoluble and are removed during developing. Other embodiments contemplatethat the dielectric layer 48 is negative tone such that portions of thedielectric layer 48 that are not exposed to the radiation 54 though thelithography mask 52 are soluble and are removed during developing.

In step 76 of FIG. 5, the dielectric layer 48 is developed. Thedeveloping can include using a wet process to remove soluble portions ofthe dielectric layer 48 after the exposure in step 74. The wet processcan include using tetramethylammonium hydroxide (TMAH) in a spin-onprocess or the like.

In step 78 of FIG. 5, the dielectric layer 48 is cured after beingdeveloped. The curing may be performed by placing the support structure46 and the dielectric layer 48 in an oven or furnace for a duration in arange from about 0.5 hours to about 5 hours, such as 1 hour, at atemperature in a range from about 100° C. to about 250° C., such as 220°C.

In step 80 of FIG. 5, the support structure 46 and the dielectric layer48 undergo a descum process. The descum process can include a plasmaprocess, such as an oxygen (O₂) plasma process. The descum process canremove residue from the developing and curing of the dielectric layer 48and can remove, for example, up to about 0.5 μm of the dielectric layer48. FIG. 4 illustrates the support structure 46 and the dielectric layer48 after the descum process. FIG. 4 illustrates a thickness loss TL ofthe dielectric layer 48, which is the loss of thickness of thedielectric layer 48 from developing, curing, and descum. Further, asillustrated in FIG. 4, no residue of the dielectric layer 48 is in thescribe line region 44 and in the vias and/or openings through thedielectric layer 48 in the first region 40 and the second region 42.

The inventors have performed the process outlined in FIG. 5 usingexposure to HMDS gas as the thin layer formation step 72 under variousconditions, and the process of FIG. 5 without the thin layer formationstep 72. The results of these processes show decreased thickness loss TLand increased layer thickness uniformity in the samples using the HMDSsurface modification. Sample 1 in Table 1 below is a dielectric layerformed without a thin layer formation step 72 being performed. Sample 2in Table 1 is a dielectric layer formed according to FIG. 5 with an HMDSgas exposure at 100° C. for a duration of 60 seconds as the thin layerformation step 72. Sample 3 in Table 1 is a dielectric layer formedaccording to FIG. 5 with an HMDS gas exposure at 120° C. for a durationof 60 seconds as the thin layer formation step 72.

TABLE 1 Sample 1 Sample 2 Sample 3 Post-Deposition Thickness 17.35 μm17.38 μm  17.4 μm Post-Deposition Thickness 1.41% 1.41% 1.41% standarddeviation percentage Post-Development Thickness 12.24 μm 14.43 μm 17.31μm Post-Development Thickness 4.05% 3.99% 1.42% standard deviationpercentage Thickness Loss  5.11 μm  2.95 μm 0.09 μm

Further, measurements were taken at various locations within the wafersof Samples 1 and 2 after curing and descum. The wafers of Samples 1 and2 contain various die-containing regions throughout the wafers. InSample 1, a thickness of the dielectric layer at the wafer center and afirst die center was 10.32 μm, at the wafer center and the first dieedge was 9.42 μm, at the wafer edge and a second die center was 10.23μm, and at the wafer edge and the second die edge was 9.91 μm. In Sample2, a thickness of the dielectric layer at the wafer center and a firstdie center was 12.31 μm, at the wafer center and the first die edge was12.21 μm, at the wafer edge and a second die center was 12.21 μm, and atthe wafer edge and the second die edge was 11.56 μm. From thesemeasurements and Table 1, it has been found that the thin layer 50formed using HMDS can decrease thickness loss of the dielectric layerand can improve thickness uniformity throughout a die region and thewafer. For example, a standard deviation of the thickness of thedielectric layer across multiple die-containing regions, e.g., acrossthe wafer, can be equal to or less than 4%, and further, can be equal toor less than 1.5%, such as 1.42%. Even further, a standard deviation ofthe thickness of the dielectric layer across one die-containing regioncan be equal to or less than 1%, such as equal to or less than 0.5%.

FIGS. 7 through 10 illustrate cross sectional views of intermediatestructures of a second generic process to illustrate various generalconcepts according to some embodiments, and FIG. 11 is a process flow ofthe second generic process according to some embodiments. As in FIG. 1,FIG. 7 illustrates a support structure 46 with a first region 40, asecond region 42, and a scribe line region 44 between the first region40 and the second region 42. As illustrated in FIG. 7 and in step 70 ofFIG. 11, a dielectric layer 48 is deposited on the support structure 46as discussed with respect to FIG. 1 and step 70 of FIG. 5. In FIG. 8 andstep 74 of FIG. 11, the dielectric layer 48 is exposed to radiation asdiscussed with respect to FIG. 3 and step 74 of FIG. 5. In FIG. 9 andstep 72 of FIG. 11, a thin layer 50 is formed on an upper surface of thedielectric layer 48 as discussed with respect to FIG. 2 and step 72 ofFIG. 5. In step 76 of FIG. 11, the dielectric layer 48 is developed asdiscussed with respect to step 76 of FIG. 5. In step 78 of FIG. 11, thedielectric layer 48 is cured after being developed as discussed withrespect to step 78 of FIG. 5. In step 80 of FIG. 11, the supportstructure 46 and the dielectric layer 48 undergo a descum process asdiscussed with respect to step 80 of FIG. 5. FIG. 10 illustrates thesupport structure 46 and the dielectric layer 48 after the descumprocess. FIG. 10 illustrates a thickness loss TL of the dielectric layer48, which is the loss of thickness of the dielectric layer 48 fromdeveloping, curing, and descum. Further, as illustrated in FIG. 10, noresidue of the dielectric layer 48 is in the scribe line region 44 andin the vias and/or openings through the dielectric layer 48 in the firstregion 40 and the second region 42.

The inventors have performed the process outlined in FIG. 11 usingexposure to HMDS gas as the thin layer formation step 72 under variousconditions, and the process of FIG. 11 without the thin layer formationstep 72. The results of these processes show decreased thickness loss TLin the samples using the HMDS surface modification. Sample 1 in Table 2below is a dielectric layer formed without a thin layer formation step72 being performed. Sample 2 in Table 2 is a dielectric layer formedaccording to FIG. 11 with an HMDS gas exposure at 100° C. for a durationof 45 seconds as the thin layer formation step 72. Sample 3 in Table 2is a dielectric layer formed according to FIG. 11 with an HMDS gasexposure at 100° C. for a duration of 60 seconds as the thin layerformation step 72. Sample 4 in Table 2 is a dielectric layer formedaccording to FIG. 11 with an HMDS gas exposure at 105° C. for a durationof 45 seconds as the thin layer formation step 72. Sample 5 in Table 2is a dielectric layer formed according to FIG. 11 with an HMDS gasexposure at 105° C. for a duration of 60 seconds as the thin layerformation step 72. Sample 6 in Table 2 is a dielectric layer formedaccording to FIG. 11 with an HMDS gas exposure at 110° C. for a durationof 30 seconds as the thin layer formation step 72.

TABLE 2 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Post-16.81 μm 16.52 μm 16.56 μm 16.61 μm 16.59 μm 16.61 μm DepositionThickness Post- 11.67 μm 12.52 μm 12.87 μm 13.58 μm 13.81 μm 13.68 μmDevelopment Thickness Thickness Loss  5.14 μm  4.00 μm  3.69 μm  2.99 μm 2.80 μm  2.93 μm

FIGS. 12 through 16 illustrate cross sectional views of intermediatestructures of a third generic process to illustrate various generalconcepts according to some embodiments, and FIG. 17 is a process flow ofthe third generic process according to some embodiments. As in FIG. 1,FIG. 12 illustrates a support structure 46 with a first region 40, asecond region 42, and a scribe line region 44 between the first region40 and the second region 42. As illustrated in FIG. 12 and in step 70 ofFIG. 17, a dielectric layer 48 is deposited on the support structure 46as discussed with respect to FIG. 1 and step 70 of FIG. 5. In FIG. 13and step 82 of FIG. 17, a first thin layer 56 is formed on an uppersurface of the dielectric layer 48 as discussed with respect to FIG. 2and step 72 of FIG. 5. In FIG. 14 and step 74 of FIG. 17, the dielectriclayer 48 is exposed to radiation as discussed with respect to FIG. 3 andstep 74 of FIG. 5. In FIG. 15 and step 84 of FIG. 17, a second thinlayer 58 is formed on an upper surface of the dielectric layer 48 asdiscussed with respect to FIG. 2 and step 72 of FIG. 5. The second thinlayer 58 may be on and/or intermingled with the first thin layer 56 inthe illustrated embodiment. The different thin layer formation steps mayuse, for example, a same formation process at different times in theprocess (e.g., steps 82 and 84 both use a HMDS gas surface modification)or may use different formation processes (e.g., step 82 uses a HMDS gassurface modification, and step 84 uses a thin photo resist). In step 76of FIG. 17, the dielectric layer 48 is developed as discussed withrespect to step 76 of FIG. 5. In step 78 of FIG. 17, the dielectriclayer 48 is cured after being developed as discussed with respect tostep 78 of FIG. 5. In step 80 of FIG. 17, the support structure 46 andthe dielectric layer 48 undergo a descum process as discussed withrespect to step 80 of FIG. 5. FIG. 16 illustrates the support structure46 and the dielectric layer 48 after the descum process. FIG. 16illustrates a thickness loss TL of the dielectric layer 48, which is theloss of thickness of the dielectric layer 48 from developing, curing,and descum. Further, as illustrated in FIG. 16, no residue of thedielectric layer 48 is in the scribe line region 44 and in the viasand/or openings through the dielectric layer 48 in the first region 40and the second region 42.

FIGS. 18 through 31 illustrate cross sectional views of intermediatesteps during a process for forming a package structure in accordancewith some embodiments. FIG. 18 illustrates a carrier substrate 100 and arelease layer 102 formed on the carrier substrate 100. A first packageregion 200 and a second package region 202 for the formation of a firstpackage and a second package, respectively, are illustrated. A scribeline region 204 is between the first package region 200 and the secondpackage region 202. One having ordinary skill in the art will readilyunderstand that scribe line regions can circumscribe each of the firstpackage region 200 and the second package region 202, and thatdiscussion relating to the scribe line region 204 similarly applies toother scribe line regions.

The carrier substrate 100 may be a glass carrier substrate, a ceramiccarrier substrate, or the like. The carrier substrate 100 may be awafer, such that multiple packages can be formed on the carriersubstrate 100 simultaneously. The release layer 102 may be formed of apolymer-based material, which may be removed along with the carriersubstrate 100 from the overlying structures that will be formed insubsequent steps. In some embodiments, the release layer 102 is anepoxy-based thermal-release material, which loses its adhesive propertywhen heated, such as a Light-to-Heat-Conversion (LTHC) release coating.In other embodiments, the release layer 102 may be an ultra-violet (UV)glue, which loses its adhesive property when exposed to UV lights. Therelease layer 102 may be dispensed as a liquid and cured, may be alaminate film laminated onto the carrier substrate 100, or may be thelike. The top surface of the release layer 102 may be leveled and mayhave a high degree of co-planarity.

Further in FIG. 18, integrated circuit dies 104 are adhered to therelease layer 102 by an adhesive 106. As illustrated, one integratedcircuit die 104 is adhered in each of the first package region 200 andthe second package region 202, and in other embodiments, more integratedcircuit dies may be adhered in each region. Before being adhered to therelease layer 102, the integrated circuit dies 104 may be processedaccording to applicable manufacturing processes to form integratedcircuits in the integrated circuit dies 104. For example, the integratedcircuit dies 104 each comprise a semiconductor substrate 108, such as abulk semiconductor substrate, a semiconductor-on-insulator (SOI)substrate, a multi-layered or gradient substrate, or the like. Thesemiconductor substrate 108 may include a semiconductor material, suchas an elemental semiconductor including Si and Ge; a compound or alloysemiconductor including SiC, SiGe, GaAs, GaP, GaAsP, AlInAs, AlGaAs,GaInAs, InAs, GaInP, InP, InSb, and/or GaInAsP; or combinations thereof.The semiconductor substrate 108 may be doped or un-doped. In a specificexample, the semiconductor substrate 108 is a bulk silicon substrate.Devices, such as transistors, diodes, capacitors, resistors, etc., maybe formed in and/or on the semiconductor substrate 108 and may beinterconnected by interconnect structures 110 formed by, for example,metallization patterns in one or more dielectric layers on thesemiconductor substrate 108 to form an integrated circuit.

The integrated circuit dies 104 further comprise pads 112, such asaluminum pads, to which external connections are made. The pads 112 areon what may be referred to as respective active sides of the integratedcircuit dies 104. Passivation films 114 are on the integrated circuitdies 104 and on portions of the pads 112. Openings are through thepassivation films 114 to the pads 112. Die connectors 116, such asconductive pillars (for example, comprising a metal such as copper), arein the openings through passivation films 114 and are mechanically andelectrically coupled to the respective pads 112. The die connectors 116may be formed by, for example, plating or the like. The die connectors116 electrically couple the respective integrated circuits of theintegrated circuit dies 104.

A dielectric material 118 is on the active sides of the integratedcircuit dies 104, such as on the passivation films 114 and the dieconnectors 116. The dielectric material 118 laterally encapsulates thedie connectors 116, and the dielectric material 118 is laterallyco-terminus with the respective integrated circuit dies 104. Thedielectric material 118 may be a polymer such as PBO, polyimide, BCB, orthe like; a nitride such as silicon nitride or the like; an oxide suchas silicon oxide, PSG, BSG, BPSG, or the like; the like, or acombination thereof, and may be formed, for example, by spin coating,lamination, chemical vapor deposition (CVD), or the like.

Adhesive 106 is on back sides of the integrated circuit dies 104 andadheres the integrated circuit dies 104 to the release layer 102. Theadhesive 106 may be any suitable adhesive, epoxy, or the like. Theadhesive 106 may be applied to a back side of the integrated circuitdies 104, such as to a back side of the respective semiconductor wafer.The integrated circuit dies 104 may be singulated, such as by sawing ordicing, and adhered to the release layer 102 by the adhesive 106 using,for example, a pick-and-place tool.

In FIG. 19, an encapsulant 120 is formed on the various components. Theencapsulant 120 may be a molding compound, epoxy, or the like, and maybe applied by compression molding, transfer molding, or the like. Aftercuring, the encapsulant 120 can undergo a grinding process to expose dieconnectors 116. Top surfaces of the die connectors 116 and encapsulant120 are co-planar after the grinding process. In some embodiments, thegrinding may be omitted, for example, if the die connectors 116 arealready exposed.

In FIGS. 20 through 26, a front side redistribution structure 140 isformed. As will be illustrated in FIG. 26, the front side redistributionstructure 140 comprises dielectric layers 122, 126, 130, and 134 andmetallization patterns 124, 128, and 132.

In FIG. 20, the dielectric layer 122 is formed on the encapsulant 120and the die connectors 116, with via openings exposing the dieconnectors 116. The dielectric layer 122 can include any of thematerials discussed for dielectric layer 48 and can be formed asdiscussed for dielectric layer 48 in any of the first, second, or thirdgeneric processes discussed above with respect to FIGS. 5, 11, and 17,respectively.

In FIG. 21, metallization pattern 124 with vias is formed on thedielectric layer 122. As an example to form metallization pattern 124, aseed layer (not shown) is formed over the dielectric layer 122 and inopenings through the dielectric layer 122. In some embodiments, the seedlayer is a metal layer, which may be a single layer or a composite layercomprising a plurality of sub-layers formed of different materials. Insome embodiments, the seed layer comprises a titanium layer and a copperlayer over the titanium layer. The seed layer may be formed using, forexample, physical vapor deposition (PVD) or the like. A photo resist isthen formed and patterned on the seed layer. The photo resist may beformed by spin coating or the like and may be exposed to light forpatterning. The pattern of the photo resist corresponds to themetallization pattern 124. The patterning forms openings through thephoto resist to expose the seed layer. A conductive material is formedin the openings of the photo resist and on the exposed portions of theseed layer. The conductive material may be formed by plating, such aselectroplating or electroless plating, or the like. The conductivematerial may comprise a metal, like copper, titanium, tungsten,aluminum, or the like. Then, the photo resist and portions of the seedlayer on which the conductive material is not formed are removed. Thephoto resist may be removed by an acceptable ashing or strippingprocess, such as using an oxygen plasma or the like. Once the photoresist is removed, exposed portions of the seed layer are removed, suchas by using an acceptable etching process, such as by wet or dryetching. The remaining portions of the seed layer and conductivematerial form the metallization pattern 124 and vias. The vias areformed in openings through the dielectric layer 122 to, e.g., the dieconnectors 116.

In FIG. 22, the dielectric layer 126 is formed on the metallizationpattern 124 and the dielectric layer 122, with via openings exposing themetallization pattern 124. The dielectric layer 126 can include any ofthe materials discussed for dielectric layer 48 and can be formed asdiscussed for dielectric layer 48 in any of the first, second, or thirdgeneric processes discussed above with respect to FIGS. 5, 11, and 17,respectively.

In FIG. 23, metallization pattern 128 with vias is formed on thedielectric layer 126. As an example to form metallization pattern 128, aseed layer (not shown) is formed over the dielectric layer 126 and inopenings through the dielectric layer 126. In some embodiments, the seedlayer is a metal layer, which may be a single layer or a composite layercomprising a plurality of sub-layers formed of different materials. Insome embodiments, the seed layer comprises a titanium layer and a copperlayer over the titanium layer. The seed layer may be formed using, forexample, PVD or the like. A photo resist is then formed and patterned onthe seed layer. The photo resist may be formed by spin coating or thelike and may be exposed to light for patterning. The pattern of thephoto resist corresponds to the metallization pattern 128. Thepatterning forms openings through the photo resist to expose the seedlayer. A conductive material is formed in the openings of the photoresist and on the exposed portions of the seed layer. The conductivematerial may be formed by plating, such as electroplating or electrolessplating, or the like. The conductive material may comprise a metal, likecopper, titanium, tungsten, aluminum, or the like. Then, the photoresist and portions of the seed layer on which the conductive materialis not formed are removed. The photo resist may be removed by anacceptable ashing or stripping process, such as using an oxygen plasmaor the like. Once the photo resist is removed, exposed portions of theseed layer are removed, such as by using an acceptable etching process,such as by wet or dry etching. The remaining portions of the seed layerand conductive material form the metallization pattern 128 and vias. Thevias are formed in openings through the dielectric layer 126 to, e.g.,portions of the metallization pattern 124.

In FIG. 24, the dielectric layer 130 is formed on the metallizationpattern 128 and the dielectric layer 126, with via openings exposing themetallization pattern 128. The dielectric layer 130 can include any ofthe materials discussed for dielectric layer 48 and can be formed asdiscussed for dielectric layer 48 in any of the first, second, or thirdgeneric processes discussed above with respect to FIGS. 5, 11, and 17,respectively.

In FIG. 25, metallization pattern 132 with vias is formed on thedielectric layer 130. As an example to form metallization pattern 132, aseed layer (not shown) is formed over the dielectric layer 130 and inopenings through the dielectric layer 130. In some embodiments, the seedlayer is a metal layer, which may be a single layer or a composite layercomprising a plurality of sub-layers formed of different materials. Insome embodiments, the seed layer comprises a titanium layer and a copperlayer over the titanium layer. The seed layer may be formed using, forexample, PVD or the like. A photo resist is then formed and patterned onthe seed layer. The photo resist may be formed by spin coating or thelike and may be exposed to light for patterning. The pattern of thephoto resist corresponds to the metallization pattern 132. Thepatterning forms openings through the photo resist to expose the seedlayer. A conductive material is formed in the openings of the photoresist and on the exposed portions of the seed layer. The conductivematerial may be formed by plating, such as electroplating or electrolessplating, or the like. The conductive material may comprise a metal, likecopper, titanium, tungsten, aluminum, or the like. Then, the photoresist and portions of the seed layer on which the conductive materialis not formed are removed. The photo resist may be removed by anacceptable ashing or stripping process, such as using an oxygen plasmaor the like. Once the photo resist is removed, exposed portions of theseed layer are removed, such as by using an acceptable etching process,such as by wet or dry etching. The remaining portions of the seed layerand conductive material form the metallization pattern 132 and vias. Thevias are formed in openings through the dielectric layer 130 to, e.g.,portions of the metallization pattern 128.

In FIG. 26, the dielectric layer 134 is formed on the metallizationpattern 132 and the dielectric layer 130, with openings exposing themetallization pattern 132. The dielectric layer 134 can include any ofthe materials discussed for dielectric layer 48 and can be formed asdiscussed for dielectric layer 48 in any of the first, second, or thirdgeneric processes discussed above with respect to FIGS. 5, 11, and 17,respectively.

The front side redistribution structure 140 is shown as an example. Moreor fewer dielectric layers and metallization patterns may be formed inthe front side redistribution structure 140. If fewer dielectric layersand metallization patterns are to be formed, steps and process discussedabove may be omitted. If more dielectric layers and metallizationpatterns are to be formed, steps and processes discussed above may berepeated. One having ordinary skill in the art will readily understandwhich steps and processes would be omitted or repeated.

In FIG. 27, pads 142, which may be referred to as Under BumpMetallurgies (UBMs), are formed on an exterior side of the front sideredistribution structure 140. In the illustrated embodiment, pads 142are formed through openings through the dielectric layer 134 to themetallization pattern 132. As an example to form the pads 142, a seedlayer (not shown) is formed over the dielectric layer 134. In someembodiments, the seed layer is a metal layer, which may be a singlelayer or a composite layer comprising a plurality of sub-layers formedof different materials. In some embodiments, the seed layer comprises atitanium layer and a copper layer over the titanium layer. The seedlayer may be formed using, for example, PVD or the like. A photo resistis then formed and patterned on the seed layer. The photo resist may beformed by spin coating or the like and may be exposed to light forpatterning. The pattern of the photo resist corresponds to the pads 142.The patterning forms openings through the photo resist to expose theseed layer. A conductive material is formed in the openings of the photoresist and on the exposed portions of the seed layer. The conductivematerial may be formed by plating, such as electroplating or electrolessplating, or the like. The conductive material may comprise a metal, likecopper, titanium, tungsten, aluminum, or the like. Then, the photoresist and portions of the seed layer on which the conductive materialis not formed are removed. The photo resist may be removed by anacceptable ashing or stripping process, such as using an oxygen plasmaor the like. Once the photo resist is removed, exposed portions of theseed layer are removed, such as by using an acceptable etching process,such as by wet or dry etching. The remaining portions of the seed layerand conductive material form the pads 142.

In FIG. 28, external electrical connectors 144, such as solder ballslike ball grid array (BGA) balls, are formed on the pads 142. Theexternal electrical connectors 144 may include a low-temperaturereflowable material such as solder, which may be lead-free orlead-containing. The external electrical connectors 144 may be formed byusing an appropriate ball drop process. In some embodiments, the pads142 can be omitted, and the external electrical connectors 144 can beformed directly on the metallization pattern 132 through the openingsthrough the dielectric layer 134.

In FIG. 29, a carrier substrate de-bonding is performed to detach(de-bond) the carrier substrate 100 from the encapsulant 120 and theadhesive 106. In accordance with some embodiments, the de-bondingincludes projecting a light such as a laser light or an UV light on therelease layer 102 so that the release layer 102 decomposes under theheat of the light and the carrier substrate 100 can be removed. Thestructure is then flipped over and placed on a tape 150. Then, asingluation process is performed by sawing 152 along the scribe lineregions 204. The sawing 152 singulates the first package region 200 fromthe second package region 202. FIG. 30 illustrates a resulting,singulated package structure. The singulation results in package 160,which may be from one of the first package region 200 or the secondpackage region 202, being singulated. In FIG. 31, the package structureis attached to a substrate 170. The external electrical connectors 144are electrically and mechanically coupled to pads 172 on the substrate170, which may occur by reflowing the external electrical connectors144. The substrate 170 can be, for example, a printed circuit board(PCB) or the like.

FIG. 32 illustrates a layout to further illustrate aspects of scribeline regions in accordance with some embodiments. FIG. 32 includespackage regions 210, such as regions 40, 42, 200, and 202 describedabove, and scribe line regions 212 y and 212 x, such as scribe lineregions 44 and 204 described above. The scribe line regions 212 y extendalong a Y-direction, and scribe line regions 212 x extend along anX-direction. Together, various scribe line regions 212 y and 212 x canencircle a package region 210.

Some embodiments may achieve advantages. By providing a thin layer,e.g., thin layer 50, on a dielectric layer that is photosensitive, theselectivity of the developing can be increased. For example, as theinventors have discovered, for a positive tone PBO material without athin layer as discussed above, a developing rate (e.g., removal ofexposed area to removal of un-exposed area) can be 1.7:0.5 (or 3.4), andfor a positive tone PBO material with a thin layer formed by HMDS gasexposure, the developing rate can be 1.7:0.36 (or 4.7). This improvedselectivity can allow for a dielectric layer that can be betterdeveloped with reduced thickness loss. For example, residue in scribeline regions and openings through the dielectric layer can be minimizedor fully removed to leave clean scribe line regions and openings whileallowing the dielectric layer to be fully developed. Further, asdiscussed previously, thickness uniformity post-development can beincreased with the use of a thin layer on the dielectric layer.

An embodiment is a method. The method includes depositing aphotosensitive dielectric layer on a support structure; forming a firstlayer on a surface of the photosensitive dielectric layer; exposing thephotosensitive dielectric layer to radiation; and after the forming thefirst layer and the exposing to radiation, developing the photosensitivedielectric layer. The support structure includes an integrated circuitdie. The first layer has a different removal selectivity than thephotosensitive dielectric layer during the developing.

Another embodiment is a method. The method comprises at least laterallyencapsulating an integrated circuit die with an encapsulant; depositing,in a chamber, a photosensitive layer over the integrated circuit die andthe encapsulant; exposing the photosensitive layer to a precursor toreact with a surface of the photosensitive layer with the precursor;exposing the photosensitive layer to a pattern of radiation; and afterthe exposing the photosensitive layer to the precursor and to thepattern of radiation, developing the photosensitive layer. One or moreopenings corresponding to the pattern of radiation are formed throughthe photosensitive layer.

A further embodiment is a method. The method comprises depositing aphotosensitive dielectric layer on a support structure; increasing aremoval selectivity between radiation exposed portions of thephotosensitive dielectric layer and radiation un-exposed portions of thephotosensitive dielectric layer; exposing the photosensitive dielectriclayer to a pattern of radiation; and after the increasing the removalselectivity and the exposing the photosensitive dielectric layer to thepattern, developing the photosensitive dielectric layer. The supportstructure has a first die-containing region, a second die-containingregion, and a scribe line region between the first die-containing regionand the second die-containing region. The removal selectivity is duringa developing process. After the exposing the photosensitive dielectriclayer to the pattern, the photosensitive dielectric layer includes theradiation exposed portions and the radiation un-exposed portions.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: depositing a photosensitivelayer over an underlying layer; forming a first layer on a surface ofthe photosensitive layer; exposing the photosensitive layer to radiationto form soluble portions and insoluble portions of the photosensitivelayer; and after the forming the first layer and the exposing toradiation, developing the photosensitive layer by applying a developer,the first layer having a different removal selectivity than thephotosensitive layer during the developing, wherein developing thephotosensitive layer comprises removing the soluble portions of thephotosensitive layer.
 2. The method of claim 1, wherein the forming thefirst layer is performed before the exposing the photosensitive layer toradiation.
 3. The method of claim 1, wherein the forming the first layeris performed after the exposing the photosensitive layer to radiation.4. The method of claim 1, further comprising, prior to the developing,forming a second layer over the first layer.
 5. The method of claim 4,wherein the forming the first layer and the forming the second layercomprises a same formation process.
 6. The method of claim 4, whereinthe forming the first layer and the forming the second layer comprisesdifferent formation processes.
 7. The method of claim 1, wherein theforming the first layer comprises exposing the surface of thephotosensitive layer to hexamethyldisilazane (HMDS).
 8. The method ofclaim 1, wherein the forming the first layer comprises modifying thesurface of the photosensitive layer by reacting a precursor with thesurface of the photosensitive layer.
 9. The method of claim 1, whereinthe forming the first layer comprises depositing a photo resist on thesurface of the photosensitive layer.
 10. A method comprising: forming anencapsulant along sidewalls of an integrated circuit die; forming afirst insulating layer and a first photosensitive layer, the firstphotosensitive layer being over the encapsulant and the integratedcircuit die, the first insulating layer being over the firstphotosensitive layer; exposing the first insulating layer and the firstphotosensitive layer to a pattern of radiation to form a pattern offirst portions and second portions; and after exposing the firstinsulating layer and the first photosensitive layer to the pattern ofradiation, developing the first photosensitive layer by applying adeveloper to the first photosensitive layer, wherein the developingremoves the first portions to expose portions of the encapsulant and theintegrated circuit die, the second portions remaining over theencapsulant and the integrated circuit die.
 11. The method of claim 10,wherein the forming the first insulating layer and the firstphotosensitive layer comprises: depositing the first photosensitivelayer; and exposing the first photosensitive layer to a gas, therebyforming the first insulating layer.
 12. The method of claim 11, whereinthe gas comprises hexamethyldisilazane (HMDS).
 13. The method of claim10, further comprising, after the developing, curing and performing adescum process, wherein the descum process thins the firstphotosensitive layer.
 14. The method of claim 13, wherein the descumprocess removes up to 0.5 μm of the first photosensitive layer.
 15. Themethod of claim 10, wherein the first photosensitive layer is removedfrom a scribe line.
 16. A method comprising: depositing a photosensitivelayer on a support structure, the support structure having a firstdie-containing region, a second die-containing region, and a scribe lineregion between the first die-containing region and the seconddie-containing region; increasing a removal selectivity betweenradiation exposed portions of the photosensitive layer and radiationun-exposed portions of the photosensitive layer, the removal selectivitybeing during a developing process; exposing the photosensitive layer toa pattern of radiation, wherein after the exposing the photosensitivelayer to the pattern of radiation, the photosensitive layer includes theradiation exposed portions and the radiation un-exposed portions; andafter the increasing the removal selectivity and the exposing thephotosensitive layer to the pattern of radiation, removing solubleportions of the photosensitive layer, the soluble portions being eitherthe radiation exposed portions or the radiation un-exposed portions inthe photosensitive layer.
 17. The method of claim 16, wherein theincreasing the removal selectivity comprises using hexamethyldisilazane(HMDS).
 18. The method of claim 16, wherein the increasing forms a layerover the photosensitive layer.
 19. The method of claim 16, furthercomprising performing a curing process and a descum process after theremoving soluble portions.
 20. The method of claim 19, wherein adifference between a thickness of the photosensitive layer afterperforming the curing process and the descum process and a thickness ofthe photosensitive layer before the curing process and the descumprocess is less than 0.5 μm.